Patch Loader

Apply unified diff patches to a module. Why?

Reasons to use patch-loader:

• minor changes needed to dependency, changes unlikely to be accepted in PR
• bug fix applied to dependency temporarily while waiting for PR to be accepted

Reasons not to use patch-loader:

• patch file becomes too complex, create a fork
• too lazy to integrate changes upstream, be a good OSS citizen

Install

npm install patch-loader --save-dev

Usage

The intended usage is with the inline syntax since it makes the most sense including the patch file in context of the file it is patching. However I don't see any reason why that should be required. There could be valid use cases for using the module.rules configuration.

Create your patch file:

[project/node_modules/foobar]$ cp source.js source.orig.js
[project/node_modules/foobar]$ # hack/test your changes to source.js
[project/node_modules/foobar]$ diff -u source.orig.js source.js >../../foobar.patch
[project/node_modules/foobar]$ mv source.orig.js source.js

Apply your patch on import/require:

import 'patch-loader?patch=./foobar.patch!foobar';
// or
const foobar = require('patch-loader?patch=../../foobar.patch!foobar');

Note: Patch file path is relative to the resource being patched. When requiring a module that defines its main entry in package.json as a file in a subdirectory of the modules directory, the relative path for your patch file should be relative to the directory containing the file, not relative to the modules directory.